<!DOCTYPE html>
<html language="en">
  <head>
    <title>a.com</title>
    <script language="javascript">
      function onLoad() {
        console.log("a_popup_a.html loaded");
        setTimeout(
            function () {
              let l = window.location;
              let url = `${l.protocol}//a.com:${l.port}/a.html`;
              console.log(`loading popup [${url}]`);
              let w = window.open(url);
            },
            100);
      }
    </script>
  </head>
  <body onload="onLoad();">
    Welcome to a.com, with a popup of a.com!
  </body>
</html>